1. Field of the Invention
The present invention relates to a solid-state imaging element including a plurality of photoelectric conversion elements arranged in rows and columns orthogonal thereto on the surface of a semiconductor substrate, and to an imaging device equipped with such a solid-state imaging element.
2. Description of the Related Art
A solid-state imaging element utilized for a digital camera detects electric charges corresponding to an image signal by means of photoelectric conversion elements. For this reason, difficulty is usually encountered in broadening a dynamic range. In order to acquire an image having a wide dynamic range, there has been proposed utilization of a solid-state imaging element having photoelectric conversion elements of relatively high sensitivity (hereinafter sometimes described as “high-sensitivity pixels”) and imaging elements of relatively low sensitivity (hereinafter sometimes described as “low-sensitivity pixels”) (see JP-A-2000-69491, JP-A-2000-316163 and JP-A-2001-8104).
Photoelectric conversion signals having different sensitivities can be obtained by means of changing the area of an aperture of the photoelectric conversion element (see, e.g., JP-A-2001-8104); changing the light transmittance of a filter provided at a position above the photoelectric conversion element (see, e.g., JP-A-2000-69491 and JP-A-2000-316163); and changing the geometry of microlenses provided at a position above the photoelectric conversion elements (see, e.g., JP-A-2001-8104).
A sensitivity ratio between the high-sensitivity pixels and the low-sensitivity pixels, both pixels being provided in the solid-state imaging element described in JP-A-2000-69491, JP-A-2000-316163 and JP-A-2001-8104, is dependent on the structure of the solid-state imaging element and hence cannot be changed. For these reasons, the sensitivity ratio cannot be changed. Therefore, difficulty is encountered in performing photographing action with an optimum dynamic range in accordance with a scene.